U.S. CITES SIGNS OF KOREAN STEPS TO NUCLEAR TEST

By DAVID E. SANGER and WILLIAM J. BROAD; Thom Shanker contributed reporting for this article.

Published: May 6, 2005

White House and Pentagon officials are closely monitoring a recent stream of satellite photographs of North Korea that appear to show rapid, extensive preparations for a nuclear weapons test, including the construction of a reviewing stand, presumably for dignitaries, according to American and foreign officials who have been briefed on the imagery.

North Korea has never tested a nuclear weapon.

Bush administration officials, when asked Thursday about the burst of activity at a suspected test site in the northeastern part of the country, cautioned that satellites could not divine the intentions of Kim Jong Il, North Korea's leader, and said it was possible that he was putting on a show for American spy satellites. They said the North Koreans might be trying to put pressure on President Bush to offer a improved package of economic and diplomatic incentives to the desperately poor country in exchange for curtailing its nuclear activities.

''The North Koreans have learned how to use irrationality as a bargaining tool,'' a senior American official said Thursday evening. ''We can't tell what they are doing.''

Nonetheless, American officials have been sufficiently alarmed that they have extensively briefed their Japanese and South Korean allies and warned them to be prepared for the political implications of a test.

On Thursday morning, Mr. Bush spoke at length about North Korea with President Hu Jintao of China, who has been his main interlocutor to Mr. Kim's government. The White House refused to say whether the two men had discussed the new evidence, focusing instead on what officials said was Mr. Bush's determination to get North Korea back to the negotiating table in six-nation talks.

American intelligence agencies have debated for years over the extent of North Korea's technical abilities, and whether it has successfully turned its stockpile of nuclear fuel into warheads. That debate has become particularly fevered since Feb. 10, when the North publicly boasted that it had manufactured weapons.

The accounts of North Korea's activities have come from three American officials who have reviewed either the imagery or the intelligence reports interpreting them. They were confirmed by two foreign officials who have been briefed by the Americans, but who cautioned that their countries had no independent way of interpreting the data.

Officials at one American intelligence agency said they were unaware of the new activity.

Since October, American officials have periodically seen activity suggesting preparations for a nuclear test, chiefly at the site in the northeast part of the country, near an area variously called Kilchu or Kilju. But in recent weeks, that activity appears to have accelerated.

Several officials said they had never before seen Korean preparations as advanced as those detected in recent days, including the digging of a tunnel. That tunnel resembles the one used in Pakistan for nuclear tests in 1998.

One of the creators of Pakistan's program, Abdul Qadeer Khan, traveled to North Korea repeatedly and has admitted to Pakistani interrogators that he supplied nuclear technology to the North, American intelligence officials said.

But officials said Thursday that they had not seen any evidence that North Korea was getting outside help with its current activity. ''What we're seeing is everything you need to test,'' said a senior intelligence official who has reviewed the evidence. ''We've never seen this level of activity.''

Asked if the intelligence agencies, which have often been sharply divided about North Korea's nuclear abilities, had differences of opinion about the satellite photographs, the official said: '' This looks like the real thing. There is wide agreement in the community.''

But another American intelligence expert noted that so far, intelligence agencies had not seen the telltale signs of electronic equipment that is often used to monitor the size and success of a test, leading to ''some debate about whether this is the real deal.''

The intelligence official who reviewed the imagery, and others familiar with the evidence, said it was entirely possible that the activity was an elaborate ruse by Mr. Kim, to strengthen his bargaining position with the five other nations in the talks that he has boycotted: the United States, China, Russia, Japan and South Korea.

Mr. Kim is considered skilled at the art of escalating a crisis, and a senior diplomat said Thursday that the United States had not raised a public alarm ''because we don't want to play his game.''

In late 2002 and early 2003, North Korea threw out international inspectors and said it was preparing to reprocess 8,000 spent nuclear fuel rods into bomb fuel, the C.I.A. and other intelligence agencies have told Congress. In recent months, they have said that they believe all 8,000 rods were turned into bomb fuel.

The head of the Defense Intelligence Agency, Vice Adm. Lowell E. Jacoby, went further last week, telling the Senate Armed Services Committee that North Korea was believed to have the ''capability'' to mount a warhead on one of its long-range missiles.